I was thinking of moving and in that case wanted to replace my ST carrier with something a bit more local. I am still working out the minor details, like where. But I will end up either in Japan, China or Vietnam, in that order.

My flights will be within those countries as well as to and from those countries. ( Tokyo - Osaka - Beijing - Hong kong - Hanoi- Ho Chi Minh )

China Southern, China Eastern, Korean Air or Vietnam Airlines?
CZ has 121 destinations on 340 aircrafts. MU has 104 destinations on 263 aircrafts. KE has 116 destinations on 132 aircrafts. VN only has 46 destinations on 66 aircrafts.

Korean air seem to have a relationship with US Bank/ Credit cards.
China Southern lets you earn miles on China Airlines, until they do join ST.

Which SkyTeam carrier has the best Asian FFP?